This patch introduces a helper to shrink unused space in the last AG
by fixing up the freespace btree.
Also make sure that the per-AG reservation works under the new AG
size. If such per-AG reservation or extent allocation fails, roll
the transaction so the new transaction could cancel without any side
effects.
Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
---
fs/xfs/libxfs/xfs_ag.c | 108 +++++++++++++++++++++++++++++++++++++++++
fs/xfs/libxfs/xfs_ag.h | 2 +
2 files changed, 110 insertions(+)
diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 9331f3516afa..a1128814630a 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -22,6 +22,11 @@
#include "xfs_ag.h"
#include "xfs_ag_resv.h"
#include "xfs_health.h"
+#include "xfs_error.h"
+#include "xfs_bmap.h"
+#include "xfs_defer.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
static int
xfs_get_aghdr_buf(
@@ -485,6 +490,109 @@ xfs_ag_init_headers(
return error;
}
+int
+xfs_ag_shrink_space(
+ struct xfs_mount *mp,
+ struct xfs_trans **tpp,
+ xfs_agnumber_t agno,
+ xfs_extlen_t len)
+{
+ struct xfs_alloc_arg args = {
+ .tp = *tpp,
+ .mp = mp,
+ .type = XFS_ALLOCTYPE_THIS_BNO,
+ .minlen = len,
+ .maxlen = len,
+ .oinfo = XFS_RMAP_OINFO_SKIP_UPDATE,
+ .resv = XFS_AG_RESV_NONE,
+ .prod = 1
+ };
+ struct xfs_buf *agibp, *agfbp;
+ struct xfs_agi *agi;
+ struct xfs_agf *agf;
+ int error, err2;
+
+ ASSERT(agno == mp->m_sb.sb_agcount - 1);
+ error = xfs_ialloc_read_agi(mp, *tpp, agno, &agibp);
+ if (error)
+ return error;
+
+ agi = agibp->b_addr;
+
+ error = xfs_alloc_read_agf(mp, *tpp, agno, 0, &agfbp);
+ if (error)
+ return error;
+
+ agf = agfbp->b_addr;
+ if (XFS_IS_CORRUPT(mp, agf->agf_length != agi->agi_length))
+ return -EFSCORRUPTED;
+
+ args.fsbno = XFS_AGB_TO_FSB(mp, agno,
+ be32_to_cpu(agi->agi_length) - len);
+
+ /* remove the preallocations before allocation and re-establish then */
+ error = xfs_ag_resv_free(agibp->b_pag);
+ if (error)
+ return error;
+
+ /* internal log shouldn't also show up in the free space btrees */
+ error = xfs_alloc_vextent(&args);
+ if (!error && args.agbno == NULLAGBLOCK)
+ error = -ENOSPC;
+
+ if (error) {
+ /*
+ * if extent allocation fails, need to roll the transaction to
+ * ensure that the AGFL fixup has been committed anyway.
+ */
+ err2 = xfs_trans_roll(tpp);
+ if (err2)
+ return err2;
+ goto resv_init_out;
+ }
+
+ /*
+ * if successfully deleted from freespace btrees, need to confirm
+ * per-AG reservation works as expected.
+ */
+ be32_add_cpu(&agi->agi_length, -len);
+ be32_add_cpu(&agf->agf_length, -len);
+
+ err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);
+ if (err2) {
+ be32_add_cpu(&agi->agi_length, len);
+ be32_add_cpu(&agf->agf_length, len);
+ if (err2 != -ENOSPC)
+ goto resv_err;
+
+ __xfs_bmap_add_free(*tpp, args.fsbno, len, NULL, true);
+
+ /*
+ * Roll the transaction before trying to re-init the per-ag
+ * reservation. The new transaction is clean so it will cancel
+ * without any side effects.
+ */
+ error = xfs_defer_finish(tpp);
+ if (error)
+ return error;
+
+ error = -ENOSPC;
+ goto resv_init_out;
+ }
+ xfs_ialloc_log_agi(*tpp, agibp, XFS_AGI_LENGTH);
+ xfs_alloc_log_agf(*tpp, agfbp, XFS_AGF_LENGTH);
+ return 0;
+
+resv_init_out:
+ err2 = xfs_ag_resv_init(agibp->b_pag, *tpp);
+ if (!err2)
+ return error;
+resv_err:
+ xfs_warn(mp, "Error %d reserving per-AG metadata reserve pool.", err2);
+ xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+ return err2;
+}
+
/*
* Extent the AG indicated by the @id by the length passed in
*/
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index 5166322807e7..f33388eb130a 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -24,6 +24,8 @@ struct aghdr_init_data {
};
int xfs_ag_init_headers(struct xfs_mount *mp, struct aghdr_init_data *id);
+int xfs_ag_shrink_space(struct xfs_mount *mp, struct xfs_trans **tpp,
+ xfs_agnumber_t agno, xfs_extlen_t len);
int xfs_ag_extend_space(struct xfs_mount *mp, struct xfs_trans *tp,
struct aghdr_init_data *id, xfs_extlen_t len);
int xfs_ag_get_geometry(struct xfs_mount *mp, xfs_agnumber_t agno,
--
2.27.0
